This page attempts to list all Sony ATRAC chipsets (CXDxxxx) found in decks and units they can be found in. It uses this a-nkmr page as it's main source. Hopefully it expands to cover all chipsets. Potentially useful thread on sonyinsider.
More technical info: https://www.minidisc.org/atrac_versions.html
http://www.puwa-net.com/minidisc/technical/atracchange.htm
https://web.archive.org/web/20010828211157/http://psych.tripod.com/md-tech.html - chart of some chip part#'s
ATRAC version
* 1
* 2
* 3
* 3.5
* 4
* 4.5
* Type-R
* Type-S
MDS-101 (1993): CXD2527R-1
Since significant bitrate capacity was devoted to error control, the sound quality was poor.
CXD2656 (NON-MDLP)
CXD2656R (MDLP)
CXD2662R (MDLP):
Sharp 5th gen ATRAC release https://web.archive.org/web/20020606052518/http://www.sharp.co.jp/sc/gaiyou/news/970730-2.htm
Sharp 6th gen process size etc https://web.archive.org/web/20020404232232/http://www.sharp.co.jp/sc/gaiyou/news/980805.htm